Solvent Descriptors Guided Wide‐Temperature Electrolyte Design for High‐Voltage Lithium‐Ion Batteries

An effective solvent screening descriptor that cominbes dual local softness and dielectric constant is demonstrated. Such a unique descriptor unveils that solvents with moderate dielectric constants and low reactivity are ideal candidates for wide-temperature electrolytes of high-voltage lithium-ion batteries, particularly for applications at high temperatures above 55 °C.

Abstract

Lithium-ion batteries are increasingly required to operate under harsh conditions, particularly at high temperatures above 55 °C. However, existing electrolytes suffer from inadequate thermal stability and significant interphasial side reactions. Moreover, there is a lack of clear guidelines for developing electrolytes that can withstand high temperatures. Here a solvent screening descriptor is introduced based on dual local softness and dielectric constant. The findings indicate that solvents with moderate dielectric constants and low reactivity are ideal candidates for high-temperature electrolytes. Among the solvents evaluated, tetraethyl orthosilicate (TEOS) is identified as a suitable option and is utilized to formulate a localized high-concentration electrolyte (TEOS-based LHCE). Remarkably, the 1-Ah LiNi_0.8Co_0.1Mn_0.1||graphite pouch cell utilizing this TEOS-based LHCE demonstrates 95.8% capacity retention after 300 cycles at 60 °C. Interphasial analysis reveals that the TEOS-based LHCE promotes the formation of thin, uniform LiF-rich interphases, effectively suppressing interfacial side reactions at elevated temperatures. This screening strategy not only enhances the understanding of electrolyte performance but also paves the way for high-throughput screening of electrolytes suitable for wide-temperature lithium-ion batteries.